Pneumatic tool.



B. BRAZELLE.

PNBUMATIC TOOL.

APPLICATION FILED IAN', 6, 101:).

Patented Mar. 23, 1915.

2 SHEETS*SHEET 1.

Eye/2%' a B. BRAZBLLE PNBUMATIC ToQL. APPLICATION FILED JAN. G. 1913,

1,132,649. Patented Mar.23,1915.

2 SHEETS-SHEET 2.

BENJAMIN BRAZLLLE, OF ST. LOUIS, MISSOURI.

PNEUMATIC TOOL.

Specification of Letters Patent.

Patented Mar. 23, 1915.

Application led January 6, 1913.- Serial No. 740,312.

-Missouri, have invented a new and useful Improvement in Pneumatic Tools, of which the following is a specification.

This invention relates to power actuated portable impact tools, such as rock drills, chipping and calking hammers, Vand the like, in which the shank of the tool is sup'- orted in the end of an engine cylinder and 1s struck repeated blows by a free piston, or hammer, therein, the reciprocation of the hammer in the cylinder being caused by Huid pressure which is usually supplied to the device through a flexible hose from a fixed source of supply.

l The object of this invention is the improvement of the power cylinder, l.and its cooperating parts, of a single acting fluid pressure engine, and the adaptation thereof to a pneumatic tool. V

The improh'ements reside in the valves and .coperating parts for directing and controlling the motive fluid which reciprocates the hammer, in the means for cushioning the valve and hammer, in the means for'supplying lubricant to the moving parts, in the means for holding the tool and for absorbingthe force of the blow when the tool is out of contact with the object being worked upon, and in the shape and arrangement of the several parts comprised in the devic as hereinafter described; and what I consider to be my. invention is particularly set forth in the appended claims.

In describing the invention, reference is had to the accompanying drawings, illus' trating one form of the invention.

In the drawings, in which like figures are used to designate like parts in all the views, ligure 1 is a top view of my device, with ihev tool removed; Fig. 2 is a central longitudinal section through the device on the line 2-2 in Fig. 1; Fig. 3 is a transverse section through the device on the line 3-3 in Fig. 2, looking in the direction of the arrows; Fig. 4 is a transverse section through the device on the line 4 4 in Fig. 1, looking in the direction of the arrows; Fig. 5 is a. central longitudinal section through the tool socket, on the linee- 5 in Fig. 2; Figs. 6, 7, and 8 are isometrlc views of the lool socket, latch, and shank ofthe tool; and Fig. 9 is a view oi the head end of the de vice With the handle broken away.

`The Idevice illustrated in the drawings comprises a power cylinder 11 having a tapped opening 12 adapted to rece-ive a connection for lan air hose or other pipe leadlng to a source of supply of fluid under pressure. The flow of air is regulated by means of a screw throttle valve 13 arranged in an annular pressure chamberY 14 in the cylinder wall. The stem 15 of the valve projects out from the'chambver through the gland 16 and is fitted with a hand wheel 17. blidable longitudinally within the cylinder, and extending nearly the entire length thereof, is a sleeve valvev 18,v coperating with the cylinder inlet and exhaust ports for controlling the flow of air to and from the cylinder. The differential piston end 19v of the hammer 20 has la. free sliding tit within the sleeve valve.v Theinner or head end of the cylinder is closed by a hollow cylinder head 21 rigidly secured thereto, and provided with a handle 22 for holding and manipulating the device. The tool end of vthe cylinder is partly closed by an annular cylinder head 23' rigidly secured thereto, `and having a hollow cylindrical outer extension 24 within which the striking end of the hammer is guided. The end of the cylinder extension 24 is `fitted with a tool socket 25 adapted to receive the -shank 26 of a chisel, drill bit, rivet set, or other impact tool for operating on stone or metal.

lThe chamber 27- in the' hollow cylinder head 21 may be filled with grease through a threaded'opening closedy by a thumb screw 28. lFrom this chamber communicating passages 29, 30, lead to the annular pressure chamber 14. The free communication octween the passages29, 30 may be closed r regulated by a thumb screw valve 31 arranged in the cylinder head.

Vvithin the cylinder.l 11,-at the outer or tool end thereof, is an annular chamber 32, in communication at its inner end with the chamber 14 by means of 'a series of small holes or ducts 33. The sleeve valve 14vhas a differential pressure flange 34 on its outer end which has a sliding it in the chamber .32,and the pressure on the inner side of this Harige always tends to hold the valve in its outer' position, as shown in F ig. 2. l The annular cylii'ider head has an annularflange portion 35y projecting within the cylinder The desired tool-a1 tensed is inserted with itsv shank in the socket 25 and its shoulders between the jaws 58, and the latch is snap in place to secure tlie vtooliii thedevice. e Y

cutting end of the 'tool' is placed in contact with the work, and tl'ne throttle lvalve 13 is .opened to any-desired'extent by means of the hand wheel. 17. The air or other fluid under pressure enters the pressure chamber 14, 'which is of considerable capacity, and

which serves asa reservoir of fluid under pressure within the device.' This is transmitted through the ports 38 to the fluid on the outer side of the piston 19, which causes the hammer to move to the inner end of its stroke. At' thesame time pressure is transmittedthrough thedncts 33 tothefluid yon the inner'side of the valve flange 34,-and

sin shown in Fig. 2, and fluid under pressure will pass through the ports -39 into the intermediate pressure chamber 40' and thence to the head end of the cylinder. As soon as the total fluid. pressure on-the inner or head end of the piston is greater 'than'the .fluid pressure on the outer annular piston area the piston will start onits outstrolce. Fluid under pressure will continue .to flow through the'ports'f38, 39 and 42 until the piston covers the'cuboflports 39-,and-at this point the further sup ly of. fluid. underv pressure to the interme iate pressure chamber 40will be cut off,"buty the fluid already in this chamber,

'andin the'head end of the cylinder will expand and 'continiie to drive .the"pistonfor ward on its out" stroke. Theluidin the annular"space within the sleeve valve is and 4is partly; drivenaouttlie l* 38 intothe' pressure cl1amli' 14which is of Aconsiderable capacity morder to accommodate the elu-rr..v Toward .theaend' of theA out stroke-of the hammer-fthe .groove 46 therein uncoversthe ports 36' leedingto the" outer end of.l the valveflangeehamber32, and admits fluid under preg sflia'e'tleret. the outer end of the sleeves' 'v hjsjof greater are-a than the inner sideoit langage-34,. the fluid pressure on'the outer-'end oigthe valve will be eater than the on the inner si e ofV the llange, wh'hWi-ll the valve tomove to the inner end of ltsstroke,

Ythus closing the inlet orts 42to the head' end of the cylinder an openin the exhaust ports 43 leading therefrom` he 'fluid 1n the head end of the eylinderwrll escape into the atmosphere, but the fluid' in the inter-me" diate .pressure chamber 40 and will be coniined therein.' 'l When the fluid pressure on' the head end "of, the piston ,has been reduced tothe .mint

pressure where it is lssfin total effect than the fluid 'pressure' on the outer' side of the piston,

which will occur at about or soon after the time that the hammer reaches the end of' lts out stroke and brings lup against the end of the tool shank, the greater pressure on the outer side of the piston will cause the hammer to move in the reverse ldirection toward the head end of the cylinder. The ports 36' will be closedby the hammer shortly after it starts on its return stroke and 'will 1 retain the fluid under let and cut-oil portspready for a vrepetition l of the cycle lof operation.'

Heretofore, single facting engines for impact tools have not been satisfactoryin serv# ice on account ofthe excessive backfpressure lressure' within the i' outer end of the valve chamber'j32 and thereupon the outer side .of the piston .on the out stroke dueto theV fact that the fluid infront of the piston cannot be driven back through the valves into the supply pipe fast enough to preventvhigh compressionin the annular space surrounding the hammer infront of the piston. In this device .this defect is chamber 14 vinto which'this fluidcan readily pass from in front of the piston.. Moreover,

avoided by the provision of the .pressure a the piston. The fluid in this intermediate chamber is not exhausted into lthe atmosphere Jwith the contents of the head end of the cylinder, `but thatremaining at the end of the power stroke'whenthe exhaust valve stro Furthermore, heretofore the proper is opened lis stored up for-the next power' lubrication of fluid-pressure engines for 1m- 'pact tools has'been diflicultto maintain'under actual working conditions. In this 'de- 3` vice the lubricant used is Anon fluid-dille or grease, which is placed-fin fthehollowcylinder head. The heat generated in the cylinf der by the compression of the fluid Vin the head Aend thereof warms the grease and i causes it to creep slowly throughthe passage 29 and past the-thumb screw'va'lve. 'Thefout l.stroke of the piston compresses :the fluid 1n front of it and drives some of it-into Vthe pressure reservoir chamber 14, and thus there is aconstant flow of fluidlinand out of the duct 30 dueto the fluctuation .of fluid pressure' within the chamber -14 during the operation of the device'. -sThis-'constantly reversin flow 'or'surging of {luid-within' the.,

duct 30 1s partly communicated `'through Athe .valve duct 2 9 ,to the fluid inA the hollow diameter, said cylinder containing an annular groove surrounding the chamber of smaller diameter and forming an extension of the chamber of larger diameter, a hollow cylindrical valve having an annular flange slidably arranged in said cylinder with one end extending into said axial recess and said flange extending into said groove, means for admitting fluid under pressure to said annular groove on each side of said flange, and 10 means for periodically exhausting fluid under pressure from one end of said groove.

Signed at St. Louis, Missouri, this thirtieth day of December, 1912.

BENJAMIN BRAVZELLE. Witnesses:

A. M. HOLCOMBE, ANDREW KEssLING. 

